This invention relates to an advantageous process for producing long-chain dicarboxylic acids from straight-chain hydrocarbons by utilizing the microorganisms as well as a method for separating and collecting the produced dicarboxylic acids.
Long-chain dicarboxylic acids are the useful material for the production of chemical products such as synthetic resin, aromatic, etc., and the demand for this material is on the increase. For these reasons, growing interest is shown lately for the method of producing such long-chain dicarboxylic acids according to a fermentation process by utilizing the microorganisms.
There has been proposed a method comprising culturing a fungus of the type capable of assimilating hydrocarbons, for example, a fungus belonging to Candida tropicalis, in a medium containing a straight-chain saturated hydrocarbon, particularly one having a carbon number of 11 to 18 as substrate, to thereby produce a long-chain dicarboxylic acid corresponding to said hydrocarbon (refer to M. Okuhara, Y. Kubochi and T. Harada, Agricultural & Biological Chemistry, Japan, Vol. 35, p. 1376(1971), Vol. 35, No. 13, p. 2033(1971) and Vol. 36, No. 3, p. 426(1972)).
However, in the heretofore proposed methods of producing long-chain dicarboxylic acids by means of fermentation techniques, including the above-said method, it is often experienced that various other germs contaminate the medium and grow in the medium in the course of culture of said type of fungus to impair the ability of said fungus, for the production of the dicarboxylic acid, resulting in very poor yield of the objective long-chain dicarboxylic acid.
Another problem in the course of the production of the long-chain dicarboxylic acid by fermentation is that great difficulties are accompanied at the steps of separation and collection of the objective long-chain dicarboxylic acid from the fermentation broth because various residual ingredients of the culture medium such as unreacted ingredients, water-soluble nutrient and eluate from the cultures exist in admixture with the objective long-chain dicarboxylic acid in the fermentation broth obtained from culture of the fungus. For example, when an extraction method is applied for separation and/or collection of the objective product, the unknown matters originating in said various substances existing in the fermentation broth are produced at the extraction interface in the fermentation broth, and such matters make it difficult to separate and collect the long-chain dicarboxylic acid from the fermentation broth.
This invention has been deviced with the object of solving the said problems in the conventional methods of producing long-chain dicarboxylic acids by use of fermentation techniques.
An object of this invention, therefore, is to provide a process for producing a desired long-chain dicarboxylic acid in a high yield without any impairment of the starting fungus by mixing and growth of other germs in the medium in the process of production of the objective long-chain dicarboxylic acid according to a fermentation method.
Another object of this invention is to provide a method whereby the long-chain dicarboxylic acid produced by using the fermentation techniques can be separated and collected from the fermentation broth in an advantageous way.
Other objects of this invention will become apparent from the following detailed description of the invention.